If you want to understand why professional tennis is vulnerable to corruption and match-fixing, spend some time with the sport's underpaid minor leaguers.

Uladzimir Ignatik, a six-foot-tall 25-year-old who, as a junior, was the top-ranked singles player in the world, did not make the main draw of the Australian Open this year. In the first round of qualifying play, he lost to Thomas Fabbiano, an Italian journeyman four inches shorter and one year older. Ignatik might have won. He took the first set 7-5, but Fabbiano fought back to win the second and third, 3-6, 2-6. Maybe the 35-degree Melbourne heat zapped his energy—Ignatik is from Minsk, Belarus, where the average January high is just above freezing. Or maybe Fabbiano just Michael Chang-ed him. Whatever. That's tennis. Ignatik packed his bags.

One week later and a world away, Ignatik took the court against a 22-year-old Frenchman named Sebastien Boltz in the first round of the MLP Cup, a tournament held in southwestern Germany. You've probably never heard it. The MLP Cup is not an ATP World Tour event. It's not even on the second-tier Challenger circuit. Instead, it's one of several hundred Futures tournaments organized by the International Tennis Federation around the world each year. Futures typically have prize pools of $10,000, though some, like the MLP Cup, offer $25,000. They are easy for top amateurs to qualify for through play-in tournaments, and they stand as the lowest form of professional tennis.

This isn't meant to diminish those who make a career out of Futures—which is to say, the majority of tennis pros. It's simply the reality of the sport: players living out of their cars, crisscrossing whatever continent they call home, playing for a cut of that $10,000, and hoping to accumulate enough points on their world ranking to qualify for something bigger. Everyone plays Futures at one point or another. Even Novak Djokovic started somewhere.

Like Ignatik, I went to the MLP Cup, only I wasn't looking to add any points to my world ranking. A week earlier, BuzzFeed had published a report about the high prevalence of match-fixing in professional tennis. While some people (myself included) criticized some aspects of the analysis, it did shine a light on an important issue, one that has been an open secret for a while: tennis is rife with corruption.

Match-fixers only have to buy a maximum of two players to get the result they want in a given singles match, which makes tennis cheaper to fix than a team sport. And because in tennis favorites lose to underdogs all the time, successful fixes can often go unsuspected. Was that a fishy result, or did he just have an off day?

Prevailing wisdom holds that the lower the stakes for the players, the easier a match is to fix. This is true in every sport. If the players are poorly compensated, they're easier to buy—especially if no one is watching. And in many jurisdictions around the world, match-fixing isn't even illegal.

Now consider a tournament like the MLP Cup. The players have driven hundreds of miles to be there, in the hopes of making a cut of $25,000. The math is disheartening. After accounting for the doubles draw, the singles players compete for 75 percent of the prize pool, of which the champion receives 14.4 percent, or $3,600. At the more typical $10,000 Futures, the winner is only making $1,400. Most of the competitors are playing for little more than gas money.

It would only take a few hundred dollars to surpass the projected earnings of most tournament participants. If you knew the outcome ahead of time, you could easily make that up on the gambling market. Let me rephrase that: You could crush on the gambling market. The percentage on your returns would make Bernie Madoff blush.

Like it or not, match-fixing is easy money.

The MLP Cup takes place annually at Racket Center Nußloch, a tennis club in Nußloch, Germany, population 10,000. It sits along a vast, green meadow; nearby, a two-lane highway bisects several acres of solar panels. Up above, an aerial tramway, not unlike a chairlift you'd find on a ski hill, carries limestone from a quarry on one side of Nußloch to the headquarters of Heidelberg Cement, in the neighboring city of Leimen, on the other.

But whatever the town lacks in size, it makes up for in tennis enthusiasm. Two of Germany's greatest tennis players were local products. Steffi Graf is from Mannheim, the nearest major city, and she trained for years in the city of Heidelberg, which is even closer. Boris Becker is from Leimen. He owns a tennis club just up the road from Heidelberg Cement—a rival, no doubt, of Racket Center Nußloch.

The entirety of the MLP Cup took place on two of the three carpeted courts in the Racket Center's indoor atrium. While the facility is top of the line—complete with a well-appointed fitness center, a restaurant area featuring an indoor pond, and a number of outdoor clay courts—it's not particularly well suited to spectating. The three courts are laid out side-by-side, and most people watched the tournament from a single line of chairs set up along an elevated walkway that ran the length of the courts' baselines. Organizers had set up a small grandstand on the third court, just in front of a wall of floor-to-ceiling windows overlooking the meadow, but when Ignatik took on Boltz, it was roped off.

If you wanted to hide in plain sight, Racket Center Nußloch would be a good place to do it.

The view from the stands at the MLP Cup. Photo by Brian Blickenstaff

Boltz stands 5-foot-10, and for the match he wore a green-and-white shirt that revealed a gold chain against his chest. His short stature—at least for a tennis player—must have reminded Ignatik of his Australian Open qualifying opponent the week before. This time, however, it was Ignatik who battled back after Boltz took the first set. The Frenchman began to crack in the second. He volleyed an easy forehand into the net, allowing Ignatik to break his serve, and immediately threw his racket at the bench. When a scorching winner burned past Boltz a few points later, he turned to the spectators on the elevated walkway. "Gut?" he asked in German. "Ja," a pensioner seated just behind him responded. "War gut."

Then Boltz looked at me. I nodded in agreement: it hit the line. Sorry, dude.

Ignatik won, 4-6, 6-4, 6-4. After the match, I couldn't find Boltz anywhere. He must have gone straight to his car. I imagined him on the highway, headed for his home near Paris, cursing his luck in French. A 10-hour drive, round trip, just for that.

Ignatik was outside the main entry, listening to something on his headphones, pacing. He wore a light blue shirt and black shorts, and appeared quite lean, with the exception of his legs, which could have belonged to a much larger man. He didn't have much time to feel good about his victory. He was due for a doubles match in about an hour.

I half expected Ignatik to shoo me away when I approached him and asked, in a hushed tone, if he had any personal experience with match-fixing. Instead, he took off his headphones.

"I had a few times when someone approached me," he said matter-of-factly. "I always reported it right away to the ITF. I guess I've just developed the reputation now as a guy who isn't interested."

I had been nervous about people overhearing us discussing something as taboo as match-fixing, but Ignatik clearly was not.

He went on to explain that it had happened twice. Or was it three times? And always over Facebook. "I had a few times where they wanted to be friends," he said. "Then they would just kind of ask if I can help them out."

Did they ever offer you money?

"No," he said, with a chuckle. "I'm sure if I'd said yes they would have, though."

Later, I approached him again with some follow-up questions. "Just ask anybody here," he said. "I'm sure everybody's had similar experiences."

Imagine you're 21 years old, and an exceptional tennis player. You feel like anything is possible if you can just build a little momentum, win some points, get to the next level. Find your rhythm, and you can have a decent career on the ATP Tour. Until then, though, money is tight—and the pressure is enormous.

In the first round of a Futures tournament, you beat some pro-am qualifier. As you prepare for your next match, a man approaches you outside your car. He tells you he'll give you €1,000 and begs you to hear him out, insisting that he's not asking you to fix anything. If you agree to split the first two sets with your opponent, he says, you get the money. The specifics are this: you lose the first, 6-3, after going up 3-0. In the second, you win by the precise score of 6-4, after breaking your opponent during his first service game. In the third set, there aren't any rules. You just play. May the best man win. See? It's not fixing. The outcome is not arranged.

Would you take the money?

From a fixer's point of view, the beauty of tennis isn't just the low cost of doing business; it's that you can fix a match without actually fixing the match's outcome, which introduces a certain degree of moral ambiguity. Is it really fixing if the last set, the deciding set, is legit? Couldn't you just look at it as a truncated competition? The better player still wins—and if you're our 21-year-old ATP wannabe, short on cash but long on ambition, winning still matters most.

"I mean obviously any fixing is bad, but a lot of the time I don't necessarily think the match result is being fixed," Ian Doward, a betting industry veteran and frequent Futures gambler, told me by phone. Doward runs a popular tennis blog, where he occasionally calls out matches he suspects are fixed.

"Especially at the lower levels, there isn't a lot of prize money as it is. Players aren't really going to want to sacrifice the chance of getting further in the tournament. Ultimately the whole point of it for them is getting their rankings up. I think it requires more money to tempt those players into actually fixing the final result. And obviously without being able to make huge amounts of money at that level, it's not worth it."

You're broke. No one is asking you to lose the whole match. Just a set. Do you cross the line? Photo by EPA

Fixing matches for the gambling market is just one form of tennis corruption. Gambling fixes might not even be the sport's biggest problem, as Marvin Netuschil, a 25-year-old German doubles player, told me.

"I was at an [event] once, in Switzerland," Netuschil said. "Before the match, my opponent told me he was injured. He told me he would tank, if I agreed to give him some of the prize money. I said no, and he played full out, but I beat him anyway."

Netuschil and his playing partner, 21-year-old Philipp Scholz, were fresh off a victory over a doubles pair who ranked more than 1,000 points lower. It was dark outside the Racket Center. The two were headed to dinner.

I ask Scholz if he'd had similar experiences.

"Every fourth tournament, you hear a story," he said.

"Most of the time, it's not betting," Netuschil said. "It's players with no points who say, 'Let me win. I need points.'"

"Some kid who needs points," Scholz said.

"Maybe they have rich parents or something," Netuschil said.

"I've never received an email or anything offering to pay me if you lose," Scholz said. "You hear lots of rumors though."

"It's easy," Netuschil said, "because the money [they offer] is more than the prize."

Being in the Racket Center's atrium was like watching tennis in a library. Spectators rarely spoke. If a whispered conversation became animated, players would turn and ask for quiet. Cell phones were silenced with haste. Minutes passed when the only sounds were the hollow thwack of ball on string, the calls from the umpires in German and English, and the players muttering in various languages. The muffled sound of a tossed coin landing, pre-match, on the courts' red-and-gray carpet was deeply unsatisfying.

On the second day of the tournament, I watched a guy named Jan Mertl, a 34-year-old who once achieved a singles ranking of 163, completely fall apart. It was notable because Mertl was the tournament's No. 2 seed, then ranked No. 224 in the entire world, and because he made a great deal of noise relative to the other players. He wasn't a grunter. He just liked to argue with the umpire.

Mertl played a huge German named Mats Moraing, ranked No. 482. The last time I'd seen someone serve as hard as Moraing in person, I was a kid watching Goran Ivanišević at an event in Los Angeles. Moraing didn't have anywhere near the consistency of Ivanišević, though. He almost double-faulted away the first game. But then, like an engine needing to warm up, he slowly got into the match. Mertl had to wait for 6-5 before he finally broke Moraing.

The second set went to a tiebreak, which Mertl lost. In the third, Mertl seemed more interested in arguing calls than actually playing. Moraing won easily, 6-3.

Professional tennis is not as lucrative as you probably think. Photo by EPA

As I watched all this, I again considered the economics of playing in Futures. The winner of the MLP Cup, as I've mentioned, was due $3,600 dollars. Mertl, on the other hand, would receive a grand total of 1.04 percent of the prize pool, which works out to $260.

Mertl turned pro in 2002. According to his ATP profile, his career earnings total $549,889 (£379,835), which sounds pretty good until you divide it by 14—and you get a yearly wage of about $39,277 (£27,123).

The economics of Mertl's career are not uncommon. When you're working full-time, traveling constantly for a $40,000-a-year career that you will be forced to retire from at some point in your 30s—and that's if you're lucky with injuries and exceptionally good—it's not hard to see how a few grand on the side would make a huge impact on your quality of life.

I want to emphasize here that I only use Mertl as an example. There's no reason to suspect he's fixing matches. To the contrary, he was nice enough to talk to me about the grind of it all after going down to Moraing. He says he's never even been approached by fixers, although he has received a threatening phone call or two from gamblers angry with him for being upset by a lower-ranked opponent.

So what's the solution?

One way to reduce the corruptibility that goes along with low wages would be to simply pay people more. Tennis observers will occasionally discuss this sort of reform; typically, the suggestion applies to the higher levels of the sport. What if instead of paying Novak Djokovic $3.85 million for his Australian Open title, you paid him, say, $2.85 million, and then gave everybody else below him, on the ATP and Challenger circuit, a relatively equal bump in pay? At least in theory, it would seem to lessen the temptation for lower-tier players to say yes to offers of money on the side.

Dan Weston is skeptical. A professional gambler who runs a service in the UK offering data-driven tips for upcoming matches, Weston thinks such a system would only "encourage failure."

"There's a reason why there's such a big discrepancy between the top players and the lower-level players," he told me by phone. "One: the Djokovics and the Federers of the world bring in a lot more commercial income, so they deserve their prize money. Secondly, and much more importantly, you can't compare [tennis] to other sports.

"People talk about golf, for example, where the world-ranked 200 player is a millionaire. Well, that's great. But if that guy played a round against Rory McIlroy, he might have like a 15-20 percent chance to beat him over 18 holes. But if a world-ranked 200 tennis player played Djokovic in a set, he'd have like a sub-one percent chance of winning the set. So there's a much bigger gap between the world 200 in tennis than there is in golf. Djokovic's odds in the first three rounds of the Australian Open were below 1.01, indicating that bookmakers thought he had a 99 percent chance of winning the match. Each one. That's three matches."

Well-paid stars like Novak Djokovic have little incentive to fix matches. But what about minor league journeymen? Photo by EPA

Instead, Weston proposed a system in which players aren't compensated for "just turning up." As things stand, players at every level earn money even if they're knocked out of the first round of a tournament. Weston argues that players instead should earn less in the opening rounds of tournaments and more in the later stages, and that those who qualify through play-ins should receive compensation, as well.

Maybe reform could have a positive effect on corruption at Challenger and ATP events, but the incentives to fix matches at the Futures level are far stronger and more obvious. Would no money for a first-round loss and $400 for a round of 16 appearance really make guys at the MLP Cup less vulnerable to a fixing payday? Would it prevent rich kids from buying points? Would it make doing the right thing worth it?

After his disappointing defeat against Moraing, Mertl showered and spoke for a time with the bartender in the Racket Club's clubhouse. Mertl had been coming here for years, and the two clearly knew one another.